Mechanically driven erasing machines, such as those driven by both AC and DC electric motors of both cord and cordless type, have been utilized for many years. An erasing machine of this nature will generally incorporate a motor driven mechanism that is disposed with a motor housing, which drive mechanism is connected to a collet chuck mechanism that receives and holds a generally cylindrical strip of erasing material, commonly known as an eraser strip. Upon manual manipulation of an on-off switch, the erasing machine, which is adapted to be hand held, may be energized to cause rapid rotation of the eraser and may be brought to bear upon a surface to be erased in order to remove undesirable markings therefrom.
Although this specification is directed generally to application of the invention to rotary erasing machines, it is not intended to so limit the scope of the invention, it being obvious that other types of motorized erasing machines may be provided with air supply mechanisms within the spirit and scope of the invention. It is contemplated that the present invention be capable of employment in erasing machines having erasers other than the elongated eraser strips commonly employed. The term "eraser strip" is therefore to be construed herein as encompassing eraser structures of any desirable configuration.
As an erasing operation is conducted, the surface being erased is eroded to some extent and erasure particles become separated from the eraser strip and become deposited on the surface being along with particles eroded from the surface, thereby contaminating the surface. Periodically, it is necessary, in order to facilitate good visibility of the surface being erased, for the operator of the machine to cease the erasing operation and remove the erasure particles from the surface by means of a brush or any other acceptable erasure particle removable device. Ceasing the erasing operation in this manner and periodically removing the erasure particles from the surface obviously detracts from the commercial effectiveness of the erasing operation, because of the amount of time utilized in brushing of the erasure particles or grit away from that portion of the surface being erased.
Another problem, encountered in the use of mechanical erasing machines, concerns the generation of heat between the rapidly rotating eraser strip and the surface being erased. When a rotating eraser strip is brought to bear upon a paper surface, to remove pencil or ink lines therefrom, a draftsman, utilizing the machine, must exercise great care to prevent the contact area from becoming hot enough to burn through the paper as well as becoming hot enough to cause deterioration of the eraser strip. When erasing ink or pencil lines from a plastic film surface, a draftsman may not be allowed to utilize a mechanical erasing device because the film is so susceptible to burnthrough due to heat deterioration of the film. It is quite difficult to erase markings from a plastic surface without generating enough heat to burn through the surface. As the draftsman applies the rotating eraser strip to the surface, it is typically necessary for the machine to be periodically lifted from the surface for cooling and this, of course, adds time to the erasing operation and detracts from the commercial feasibility thereof.
Heat generated during an erasing operation may cause burnishing or slight discoloration of a paper surface, being erased, and may detract from the ability of the paper to receive ink or pencil markings after being erased. It may be necessary, after utilizing a mechanical eraser, for erasing pencil or ink lines on paper, to clean the erased surface with a manually applied eraser before applying ink or pencil lines thereto. Of course, between the mechanical and manual erasing operations, it is necessary to brush away the erasure particles. Considerable time may therefore be expended in the drafting and erasing operation which is, of couse, undesirable.
Another factor that may detract from mechanical erasing operation, is the amount of wear that occurs on rotating eraser strips because of the great amount of heat that is generated. Frequently, a rapidly rotating eraser strip will become sufficiently heated during an erasing operation that the eraser material will break down and crumble away quite rapidly. Heat deterioration of the eraser strip in this manner obviously substantially increases the cost of the erasing operation, as well as substantially increasing the amount of erasure particles that become deposited on the surface being erased, which particles of course must be brushed away before a drafting operation can be continued.
A draftsman drawing with pencil or ink on a paper surface will typically employ the following erasing sequence during drafting operations:
1. Pick up erasing machine.
2. Erase.
3. Lay erasing machine down.
4. Pick up brush.
5. Brush erasure particles away from the erasing area and inspect erasure.
6. Lay brush down.
7. Pick erasing machine up again.
8. Touch up incomplete erasure or erase over lines again to improve quality of erasure.
9. Lay erasing machine down.
10. Pick up brush.
11. Brush erasure particles away from erasing area and reinspect erasure.
12. Lay brush down.
13. Repeat steps 7-12 if necessary.
14. Begin drawing again.
It is therefore a primary object of the present invention to provide a novel air blowing erasing machine that provides the draftsman with the capability of utilizing the following sequence during erasing operations.
1. Pick erasing machine up.
2. Erase and inspect erasure simultaneously, because grit or erasure particles will have been removed from the surface being erased during application of the eraser strip to the surface.
3. Lay erasing machine down.
4. Begin drawing again.
It is a further object of the present invention to provide a novel mechanically driven air blowing machine such as an erasing machine that gives the erasing machine the capability of directing a flow of compressed air against the surface being erased, immediately adjacent the point of contact between the eraser strip and the surface, which flow of compressed air is sufficiently great to blow erasure particles away from the area being erased, thereby providing the draftsman with good visibility of the area being erased at all times.
It is an even further object of the present invention to provide a novel mechanically driven air blowing machine having the capability of developing a flow of gaseous medium for achieving cooling of the contact area between the tool carried by the machine and the surface on which work is being done, thereby preventing over heating of the work surface and preventing excessive or erosion of the tool carried by the machine during the working operation.
It is an even further object of the present invention to provide a novel mechanically driven air blowing machine having the capability of developing a flow of compressed air for use in general blowing, such as blowing chips, grit or cuttings from a surface being machined, sanded or otherwise worked upon.
Among the several objects of the present invention is noted the contemplation of a novel mechanically driven air blowing erasing machine, which promotes optimum erasing at nominal eraser strip cost by preventing excessive wear of eraser strips during erasing operations.
It is an even further object of the present invention to provide a novel mechanically driven air blowing erasing machine incluing an air supply mechanism that may be disposed within the erasing machine and may be driven by the motor of the erasing machine.
It is also an object of the present invention to provide a novel air blowing erasing machine utilizing an eccentric pump for causing pulsating flow of air which pump is capable of substantially vibration free operation.
It is also an object of the present invention to provide a novel air blowing erasing machine that may be supported in proper position to be readily grasped by a draftsman when not in use.
Other improvements of the function and facility of design will become apparent to one skilled in the art upon an understanding of the illustrative embodiments about to be described and various advantages, not referred to herein, will occur to one skilled in the art upon employment of the invention in practice.